Interest in improving vehicle performance has increased dramatically in recent years with one result being the development of a variety of automatic systems for maintaining and controlling various engine parameters.
Of particular interest in the recent past has been the desire to position the incipient or engagement starting position of the clutch so that it is optimized according to particular engine conditions such as engine speed, transmission oil temperature and clutch wear existing at the time. For example, it may be desired that the disengaged position be advanced a predetermined amount toward the engaged position to account for wear or in a direction away from the engaged position in the case of increasing transmission oil temperature or higher engine speeds.
One example of a method for controlling friction clutch operation is described in published British application GB 2231116A. Here, apparatus and method are disclosed for optimizing the engagement position of a friction clutch to achieve optimum driving comfort and to provide smooth driving operation resulting in lengthening the service life of the clutch as well as the life of the vehicle itself. More particularly the apparatus and method include means for detecting engine speed and transmission gear speed; means for measuring the clutch operating path; means for detecting the position of the fuel supply mechanism (i.e. throttle valve position); means for detecting the accelerator pedal position; means for detecting the idling position of the fuel supply mechanism; means for detecting the transmission position with neutral; means for detecting transmission gear change intent; a device for detecting the throttle valve end position; and an engine temperature measure. Signals provided by the above sensors are processed to provide an optimum position to which the friction clutch is moved between an open and closed condition by a piston driven mechanism so that the friction clutch's subsequent movement therefrom to a closed (engaged condition) is accomplished with optimal smoothness.
Another example of a clutch control system is described in U.S. Pat. No. 4,678,069, the disclosure of which is incorporated herein by reference. Here, transmission oil temperature and transmission input shaft speed are both used as correction factors for adjusting the clutch starting position.
Yet another example of an automatic clutch control system is disclosed in U.S. Pat. No. 5,029,678, the disclosure of which is incorporated herein by reference. Here, engine speed, transmission input shaft speed and amount of accelerator pedal depression are used to adjust the clutch's engagement starting position.
The system of the present invention utilizes sensed parameters of engine speed, transmission input shaft speed, actual and predetermined clutch position in conjunction with optional sensed or calculated parameters such as rate of change of transmission input shaft speed, transmission oil temperature, rate of change of clutch position in a control system for optimizing the clutch engagement start position under various operating conditions that uniquely utilizes two different rates of clutch engagement as part of a program for determining optimum clutch incipient starting position. The system of the invention further preferably establishes and stores fault codes in memory indicative of when the incipient clutch position for particular sensed operating conditions (when the transmission is not in neutral) differs by more than a predetermined fraction that is less than one.